VOGONS


First post, by RetroGameplayer

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Anyone have experience with using these acrylic sprays to protect plastics on PC cases, consoles, etc from yellowing? I find the best medicine is of course to keep them away from sunlight, but even ambient light seems to have long-term effects. Wondering if anyone can recommend or not recommend use of these sprays, whether they cause damage to surfaces of interest, etc.

https://www.amazon.com/Krylon-K01305-Coatings … ps%2C139&sr=8-2

Reply 1 of 11, by Matchstick

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UV is not the cause of yellowing.
Direct sunlight actually has a bleaching effect, not yellowing.
Heat is the cause. Cause even stored in a box in an attic, plastic will yellow...
The only factor is the ambient temp in an attic is very high.

When it comes to retro brighting or vaporbrighting, the best results are actually due to doing it at a higher temp than room temp (120F/45c)

Also Acrylic Clear Gloss paint is not a solution.

Use this instead: https://www.amazon.com/303-Dust-Lint-Staining … t/dp/B00JG3OIFU

Reply 2 of 11, by kingcake

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Matchstick wrote on 2024-03-30, 22:17:
UV is not the cause of yellowing. Direct sunlight actually has a bleaching effect, not yellowing. Heat is the cause. Cause even […]
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UV is not the cause of yellowing.
Direct sunlight actually has a bleaching effect, not yellowing.
Heat is the cause. Cause even stored in a box in an attic, plastic will yellow...
The only factor is the ambient temp in an attic is very high.

When it comes to retro brighting or vaporbrighting, the best results are actually due to doing it at a higher temp than room temp (120F/45c)

Also Acrylic Clear Gloss paint is not a solution.

Use this instead: https://www.amazon.com/303-Dust-Lint-Staining … t/dp/B00JG3OIFU

I have retrobrighted countless computers that only yellowed where sunlight hit them through a window.

Reply 3 of 11, by kingcake

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RetroGameplayer wrote on 2024-03-30, 17:07:

Anyone have experience with using these acrylic sprays to protect plastics on PC cases, consoles, etc from yellowing? I find the best medicine is of course to keep them away from sunlight, but even ambient light seems to have long-term effects. Wondering if anyone can recommend or not recommend use of these sprays, whether they cause damage to surfaces of interest, etc.

https://www.amazon.com/Krylon-K01305-Coatings … ps%2C139&sr=8-2

303 Aerospace Protectant

Reply 4 of 11, by Dothan Burger

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kingcake wrote on 2024-03-30, 22:28:
RetroGameplayer wrote on 2024-03-30, 17:07:

Anyone have experience with using these acrylic sprays to protect plastics on PC cases, consoles, etc from yellowing? I find the best medicine is of course to keep them away from sunlight, but even ambient light seems to have long-term effects. Wondering if anyone can recommend or not recommend use of these sprays, whether they cause damage to surfaces of interest, etc.

https://www.amazon.com/Krylon-K01305-Coatings … ps%2C139&sr=8-2

303 Aerospace Protectant

303 aerospace is amazing. It's the only rubber and plastic protection I use, I don't know what it will do for cases but it can't hurt.

Reply 5 of 11, by Shponglefan

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Matchstick wrote on 2024-03-30, 22:17:

Heat is the cause. Cause even stored in a box in an attic, plastic will yellow...
The only factor is the ambient temp in an attic is very high.

Is heat really the cause?

I've noticed that with old cases, areas that were shielded from oxidation tended to not yellow versus areas that were exposed. This is obviously not a heat related issue, since the case would have likely been a relatively uniform temp.

I also have a retrobrighted case that was stored in my basement in cool temperatures (below 20 C), and it has gradually re-yellowed.

Pentium 4 Multi-OS Build
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Reply 6 of 11, by RetroGameplayer

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Thanks for the 303 Aerospace product suggestion! Curious is there something people use to minimize bleaching of big box PC games? Again, I've noticed even strong ambient light can fade those over time and I'd hate to keep them all out of sight in a closed cabinet. I imagine a glass door would help some (UV tints tend to be too dark though)... but any added protection would be worthwhile.

Reply 7 of 11, by Dothan Burger

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RetroGameplayer wrote on 2024-03-31, 12:57:

Thanks for the 303 Aerospace product suggestion! Curious is there something people use to minimize bleaching of big box PC games? Again, I've noticed even strong ambient light can fade those over time and I'd hate to keep them all out of sight in a closed cabinet. I imagine a glass door would help some (UV tints tend to be too dark though)... but any added protection would be worthwhile.

Don't use on clear plastic. I haven't tried it myself, but I've heard it can fog clear plastic.

Reply 8 of 11, by chinny22

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Shponglefan wrote on 2024-03-31, 02:58:
Is heat really the cause? […]
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Matchstick wrote on 2024-03-30, 22:17:

Heat is the cause. Cause even stored in a box in an attic, plastic will yellow...
The only factor is the ambient temp in an attic is very high.

Is heat really the cause?

I've noticed that with old cases, areas that were shielded from oxidation tended to not yellow versus areas that were exposed. This is obviously not a heat related issue, since the case would have likely been a relatively uniform temp.

I also have a retrobrighted case that was stored in my basement in cool temperatures (below 20 C), and it has gradually re-yellowed.

My experience seems to back this up, but haven't looked into it
I had some plastic parts in a box in a cupboard in a caravan that yellowed pretty bad, so no chance of sunlight but a caravan in Australian summertime defiantly gets hot.
I've also had parts yellow in sun, but if you think about it. Something sitting in direct sunlight for a few hours each and every day is going to be hotter than the parts in the shade.

Has been quite a few reports that retrobright is only a tempory fix which is 1/2 the reason I haven't bothered with it myself.

Reply 9 of 11, by wierd_w

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Shponglefan wrote on 2024-03-31, 02:58:
Is heat really the cause? […]
Show full quote
Matchstick wrote on 2024-03-30, 22:17:

Heat is the cause. Cause even stored in a box in an attic, plastic will yellow...
The only factor is the ambient temp in an attic is very high.

Is heat really the cause?

I've noticed that with old cases, areas that were shielded from oxidation tended to not yellow versus areas that were exposed. This is obviously not a heat related issue, since the case would have likely been a relatively uniform temp.

I also have a retrobrighted case that was stored in my basement in cool temperatures (below 20 C), and it has gradually re-yellowed.

There have been some ... not well controlled... experiments concerning this. Since what is mostly out there is idle (if somewhat informed) speculation on the matter, I will throw my own in as well.

Heat has been demonstrated to be a common factor in most yellowing. even with devices that are in the sunlight, you will find that the areas MOST yellowed (or yellowed the fastest), are areas where heat was radiated from within the device.
Other experiments have had yellowing happen with just the heat, such as the afore mentioned "In a box, in the attic" anecdote.

What all of these have in common is heat, plus exposure to atmosphere.

I would propose that what is happening, is a breakdown and release of polymer's plasticisers and hardeners, which migrate to the surface, oxidize, and turn brown. Heat facilitates this migration, and upon exposure to atmosphere, these compounds break down. Exposure to UV light further catalyzes this reaction.

This would explain why "Sunlight made it more noticeable", "Stickers seem to stop it", "It still happens in the darkness in the attic", etc are all True.

I would say that the Retr0brite process does not "Reverse" the process, so much as it further, and more aggressively, breaks the more complex oxygenated complexes that form in the top few microns of the plastic down into simpler, smaller oxygenated compounds, which removes the yellowness-- but still leaves the plastic with less plasticizer in it, (which would be consistent with the retrobrited plastics being more brittle, and prone to scuffing)

Compare: Linseed oil hardens into a complex chaotic polymer film on exposure to oxygen in the atmosphere. Catching it on fire is ALSO oxidation, but does NOT produce said film-- it produces smaller molecules.

Depending on the plastic, and its characteristics (concerning thermal stability), heat alone (in conjunction with the hydrogen peroxide) is sufficient to get very good results. (Some plastics are not tolerant of the temperatures required, and will deform!! Others, are perfectly OK with some pretty warm solutions, and can be brightened very effectively indoors with just a covered saucepan on simmer full of pharmacy grade peroxide.) For the less therm0stable plastics, you need the UV light.

In both cases, all that is really happening is that the reactivity of the oxygen is given a boost by an outside energy source.

I'd like to see some more structured experiments performed, with various kinds of applied energy added, such as low-level electrolysis of cool solutions, exposure to more ionized oxygen species (like ozone, or other peroxides besides hydrogen), etc, with careful notes taken about temperature and energy supplied, to determine where the "magic threshold" is.

Reply 10 of 11, by Matchstick

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kingcake wrote on 2024-03-30, 22:28:

I have retrobrighted countless computers that only yellowed where sunlight hit them through a window.

Note, windows in a home generally have UV resistant coating... which leaves the next thing... Direct sunlight through a window still exposes what it hits with heat.

Reply 11 of 11, by kingcake

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Matchstick wrote on 2024-04-02, 20:19:
kingcake wrote on 2024-03-30, 22:28:

I have retrobrighted countless computers that only yellowed where sunlight hit them through a window.

Note, windows in a home generally have UV resistant coating... which leaves the next thing... Direct sunlight through a window still exposes what it hits with heat.

Not in the 80s and 90s in the US.